Hearing aid



FIG. 1 is a perspective view of a hearing aid showing the design;

FIG. 2 is a first side view thereof;

FIG. 3 is a second side view thereof;

FIG. 4 is a bottom view thereof;

FIG. 5 is a top view thereof;

FIG. 6 is a rear view thereof; and,

FIG. 7 is a front perspective view thereof. 

CLAIM The ornamental design for a hearing aid, as shown and described. 